1. Technical Field
The present invention relates to an image forming apparatus for forming high quality images.
2. Description of Related Art
Generally speaking, an image forming apparatus first charges a photosensitive member and then erases electric charges in accordance with a document image, in other words, conducts an exposure process, in order to form an electrostatic latent image. Using a developing device, toner is then attached to the electrostatic latent image formed on the photosensitive member. The toner thus attached to the photosensitive member is then transferred to a transfer member such as an intermediate transfer belt and a sheet of paper to produce a printed image.
At this point, if the amount of electric charges is more than the appropriate amount, toner particles of the same polarity repulse each other causing them to be displaced from the positions they are supposed to be, which in turn causes scattering (scattering transfer) and distortion of printed images (image distortion) sometimes. Scattering transfers and image distortions occur more conspicuously in case of high contrast toner images, such as character images, than in photographic images. Therefore, various existing technologies for suppressing scattering transfer and the like have been developed primarily for such high contrast toner images.
For example, the technology disclosed by Publication of Unexamined Japanese Patent Application No. 2006-138891 is intended to lower the electric charge of toner formed on the photosensitive member or the intermediate transfer belt to a proper value by using a static eliminator and to prevent the repulsion between toner particles.
However, since the charge amount required varies with each type of image, adjusting the charge amount for a specific image by means of a static eliminator, the adjusted charge amount for another image can be insufficient or excessive to cause scattering transfer.